Process of making lock-seams



June 11, 1935. Q. s. NOBLITT PROCESS OF MAKING LOCK SEAMS Filed Jan. 9, 1935 fi I Patented June 11, 1935 UNITED. STATES,

Noblitt Sparkslfidustries, a corporation of Indiana Application January 9., 193 3 ,SerialQNo.. 650,751. 1 a 7 5 Claims.

invention is: concerned with; the applica-. tion. an attachment. of. a sheet-metal cap. to the open. end. of a sheet-metal tube or casing. in situ.-. ations. where, it is undesirable to-. have on the finished assembly an, outwardly projecting flange formed by. the interlocked. seam between the cap and. the tube or casing; Where it is permissible tutjng the seam. difficulties are experienced in securing a. tight J'oint. One method used in the past, for interlocking,- theedges of a cap and. tube while.- avoiding theexistence of an outwardlyp rojeoting flange hasbeen toforma lock sea-m extending radially out from the tube, and then to, fold this seam backwardly along the tube;

I have found itpractically impossible to make an efiective, leak-proof seamby thismethod for,

no matter how tightlythe seam is compressed to effiect. a seal while the seamprojects outwardly, it is opened up at. lea-stslightly while it is being folded over the tube. I It is the object of'my invention toproduce-a lock-seam between a tube or casing and an end:-. closure therefor in whichthe seam, while satisfactorily leak-proof, will lie closely- -alongthe wall of the tube or casing.

In carrying out, my object I turn the edge of the tube or casingoutwardly and backwardly to form a conical flange, and I form on the cap a flange having a conical portion complementaryto the flange on the tube. The cap is placed; over the end of the tube and the rim of the capflange turnedinwardlyback oi the flange on the tube, thus. loosely. connecting the 08 p: and tube together. In, the next; operation, the iii-turned of the cap=flange is. bent further inwardly. Ito engage the back surface oi the flange on the tube, and the seam thus. formed is compressed. The seam thus. provided is then bent backwardly as a, whole into contact with the wallof thet-ube.

The accompany ng drawin l ra s my invention: F 1; is: a r mentalaxial s t on through, the cap and tube and through the dies employed in efieicting the first, assembling operathan, the dies being shown only partly closed; Fig. 2 is a view similarto 1, but showing the dies completely closed Fig. 3 is a fragmental axial section showing the. second setiof and.

e o erationg e iorm thereby: g. 4 is, a i

lar View illustrating a set of dies which, while bending the flange. forming the lock sean rearwa-rdly; also compress the steamy Fig. 5 illus trates the final-set of dies usedv impartially closed position; Fig. 6 is a view similar to Fig 5;. but showing thed-ies completely closed; and! Fig. 7: is acomplete axial section-showing theassembled tube and cap in its final condition. An article of -the type withwhich my invention isconcerned is; illustrated in; Fig. 'l and com-- prises a sheet-metal tube or casing l: having sheet-metal;end closures, or ca'psl I. It will be noted; that the caps II are secured in place on the ends of-thetubeor 'casinglafl' by interlocked seams which. lie axially inwardly of the central portions of the caps and which do, not project materially outwardly beyond the: wall of the tube 1'0. w

Fig. 7,the tube and caps are separately formed. The edge of the tube-wall at'ea'ch 'end of the tube is bent outwardly and backwardly, as by rolling, to form a'conical flange 12 which slopes: radially outwardly and axially inwardly of the tube. Each cap H is formed with an annular flange having three portions: First, an inner and relatively narrow. plane portion 13; second, an intermediate'c'onical portion M- which is tapered complementarily to .the fiangeIZ' on the tube l0-; and-third, anouter. portion which issubstantlallycylindrical and which extends axially outwardly-fromthe body of the cap it. I

The dies used in the first assembling operation are illustrated in Figs. 1 and 2 and comprise an inner die 20, and an outer die-21.. The former is shaped to engage the inner portion l3 and the intermediate portion [4 of the, cap-flange. The outer e 2 has, a ntra p nin w ic ceives. the shell. or cas n 0... he per n o mening in the die 2! is counterbored 'toa diameter surficientjto receivethe outerportion I5 of the cap-flange. The upper surface'zlof-theshoulder'forming the bottom of the counterbore slopes inwardly and. downwardly, as is clear from Fig}; '1. When the tube Ill and cap-ll are to be assem bled, the tube is placed in the lower die ZI-with theflange l2 lyingin the counterbored portion of: the recessv in the die 2|; andthe cap II isthen dropped over the upper end of the tub,e.=' The parts are shown in thispositionin Fig. 1. The dies and 2- l, are-then brought together, the inclined surface 22 of the die 12! serving-to force the outer portion l5 of the cap-flangeinwardly 20, In producing a seam of the type illustrated in a flange. I

The loose assembly effected by thefirst opera-r tion is then transferred to the second set of dies illustrated in Fig. 3. This second set of dies comprises an inner die 30 and an outer die 3|. The."

former is provided with a conical face adapted to engage the back of the intermediate portion I4 of the cap-flange. The outer die 2| has'a central opening to receive the shell;or tube il-and, surrounding such opening is an upwardly projecting annular rib 32 the outer surface of which is conical and tapered complementarily to the face" of the inner die 30. i l

When the dies illustrated in Fig. ,3 are brought together with atube and capassembly between them, the outer portion I of the cap-flange is bent upwardly into engagement with the back: of theflange on the tube I0, and the intermediate and outer portions of the cap-flange are forced toward each other to'grip the flange on the tube Ill betweenthenn 4 'A third set of diesemployed is illustrated in Q I, Fig. 4 and comprises' an inner die 40 and an outer 30 die 4|. Like the die 3H, the die AI has a central opening to receive the tube I0 and an upwardly dies 30 and 3| in that the'conical operative faces of the die 40 and the rib 42 are more nearly cylindrical. As a resultof ther'action' of the dies 40 and 4 I, the seam formed by the interlocking of the tube I0 and cap" I I .is bent'loackwalrdly more nearly into parallelism with the 'wall of the tube It! and at the same time is compressed and tightened.

The final assembling operation isperformedin the dies illustrated in Figs-5 and 6. This set of dies comprises aninnerdiezin-and an outer die 5!; The inner, die 50 is annular in shape and is formed to, engage the center portion of the cap II near the edge thereof and also to engagethe inner portion I3 of the cap-flange. Like the other outer die described, the die 5 I hasa central opening adaptedtoreceive the shell I 0, the upper end of this opening being counterbored; The counterbored portion-of the opening fofthedie 5 I may be regarded as" divided axially into three sections; first, an upper cylindrical sectidn 52 having adi- 55' ameter sufiicientto'receive the'seam formed by the dies!!! and M; second, alower' portion 5 3, whichis also cylindrical but which has a diam-f eter only slightly larger than the outer diameter of the tube I0; and third, an intermediate conical portion 54 which tapers from the larger-diameter portion-52 to the smaller, diameter-portion 53. I As-is clearly evident from Figs/5 and.6;f.the' tube and cap assembly, after the operation pen formed by the die illustrated in Fig.4,- is trans,-

ferred to the dies illustrated in Figs-5 and 6.-

As these dies are brought togetherthe outer edge of the seam formed by the interlocking flanges;

of the tube and cap is forced inwardly by the conical'wall 54 of the die; 5|. -Whe'n theidies are completely closed, this seam hasbeen broughtinto parallelism with the wall of'thetube II], as is clear from Fig. 6; Preferably, the diameter of thelower' portion 53 0f the die 5I is'such as to 1 displacethe metal atthe'end of the tube III inof end closurestothe shells of mufliers used with internal combustion engines.

I claim I as my invention: -f;*1.'Th6 process of securing together a sheetmetal tube and a'cap for one end thereof, which comprises separately forming on the end of the tube and at theedge of the cap complementary conical flanges, the flange on the cap being wider than the fiangeon the tube, bringing the cap and tube together with said flanges in' engagemerit and the rim; of the cap-flange projecting outwardly beyond the flange on the tube," fold-11 ing the projecting rim' ofthe cap-flange inwardly beneath'the tube flange, compressing the seam' thus formed, and then folding such seaminward-f ly into engagement with the wall of the tube andf subjecting the exterior of t the seam to inwardly directed radialpressureto cause a permanent 2 The process of securing together a sheetmetal tube and'a cap for one end thereof, which comprises'separately forming on'theendjof the tube andfat the edge of the cap complementary" flanges, the flange on thecapbei ngwider than the flange'on the tube, bringing the capfand'jtub'ei together with saidfia-nges in'engag'ement and the rim of the cap-flange projecting outwardly beyond'the flange on the tube, folding-the'projecting rim of the cap-flange inwardly beneath the tube flange," compressing the seam-thus formed, and then folding such seam'mwridiy into engagement with the wall of thetube and subjecting' the' exterior of the seam to inwardly directed radial pressure to causea permanent reduction in'the internal diameter or theftubef in the plane of the seam. 3 5

3. The process set-forth in claim 1 the that the seam is compressed each step. I

'4. The process set forth in claim'2 with the additions that the operation of folding the seam inwardly is performed in' a plurality of steps and that the seam is compressed at 'theconclusion ofeach'stepi H A:

5. The process' of securing together a sheet"- metal tube and a cap for one end thereof, which comprises separately forming on' the end 'of the tube-and at theiedge of the capcomplementary flanges, the flange onthe cap being wide'rtha'n thefla'nge on the tube, bringing the cap and tube together with said'flanges ,in engagement and the rim of the cap-flange projecting outward- 1y beyond the flange on the-'tube, foldingthe projecting rim"of 'thecap-flange inwardly beneath the 'tube flange, compressing the seam-thus formed, and then' foldingsuch'seam' inwardly into engagement withithe wall of the-tubewhile' maintaining the" cap and tube free frominternal support at the seam. l v-I ""QUINTIN G. NOBLITT; Q

at "the: conclusio'n'pf reduction" in the internal diameter of the tubef in thepla'ne of'the seam.- projecting annular rib 4-2 surrounding such opening. The dies All and I I ,however, differ from the additions thattheoperation of folding the sear'n' 503 inwardly is performed in a plurali'ty'of steps and": 

